Seismic waves are waves produced by earthquakes. This occurs
when rocks under the earth suddenly break or explode. There are two MAIN TYPES
of seismic waves called body waves and surface waves.
<span>Body waves have the capacity to travel through the Earth's
inner layers. They have a higher frequency and they are the ones that first
occur under water at the onset of an earthquake. They can be subdivided
into two types, the primary and secondary waves that arrive at seismic records
one after another.
Surface waves can only traverse through the surface of the planet like ripples
in the water. These waves can easily be detected on a seismogram result. These
waves arrive after body waves and they are the ones mostly responsible for
damages and destruction bought by earthquakes.</span>
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Mitosis is simply a stage in a cells life cycle, which could be broken down further into stages of mitosis. The rest (so not mitosis) is know as Interphase and is where the cell does its normal function, so if it's the cell is in a region of muscle it would contract/relax as normal etc.
Immediately before mitosis (or M phase) is what's know as G2 phase, where the G stands for growth and is where particular gene pathways are expressed to promote growth of the volume of DNA (chromosomes are duplicated, so from 46 to 92). At the end of this stage is a checking process where the DNA is scrutinised for any errors, if all is okay then the cell can proceed to mitosis, if not then the process is stopped so that errors in copying the DNA can be fixed. This is know as a restriction point and the cell must meet the requirements to pass. This is often seen as a way cells can prevent damage being replicated and therefore interfering with normal cell processes. When cells are cancerous they are able to override this and therefore divide and spread the damaged DNA.
